Pressure sensitive inked fabric and method of making



Feb. 7, 1967 D. A. NEWMAN 3,303,045

PRESSURE SENSITIVE INKED FABRIC AND METHOD OF MAKING Filed Oct. 4, 1963 INVENTOR- Douglds A../VeW/27a/7 United States Patent 3,3i)3,045 PRESSURE SENSITIVE INKED FABRlC AND METHOD 0F MAKING Douglas A. Newman, Glen Cove, N.Y., assignor to Columbia Ribbon and Carbon Manufacturing Co., Inc,

Glen Cove, N.Y., a corporation of New York Filed Oct. 4, 1963, Ser. No. 313,803 11 Claims. (Cl. 117-361) The present invention relates to novel inked fabrics for duplicating purposes such as typewriter ribbons, chain printer ribbons and the like, and to the novel method for preparing such inked fabrics.

Conventional inked fabric ribbons comprise a number of filaments of natural or synthetic polymer which are matted into fabrics or which are more commonly wound together to form multi-filament strands which are woven into fabrics and impregnated with a conventional fluid ink comprising oil and coloring matter. Such ribbons are constantly being improved to some degree from the standpoint of increasing their ink capacity without degrading their imaging properties with respect to sharpness and cleanliness, but such improvements are relatively minor in view of the basic limitations arising from the size and number of filaments which can be used in such conventional ribbons and the fact that any variation in the denier or caliper of a fabric ribbon generally results in an improvement of the writing properties and a reduction of the ink capacity, or vice versa.

It is an object of the present invention to provide novel fabric ribbons which have an increased ink capacity and improved imaging properties without the necessity of changing the number or size of the filaments used or the caliper of the ribbon.

It is another object of this invention to provide inked ribbons based upon fabrics which are exceptionally light in weight and exceptionally ink-receptive and which have sufficient strength to withstand the pressures exerted by a type bar or similar imaging device.

It is an advantage of this invention that the porosity of the present ribbons permits the type bar or similar imaging device to compress the ribbon so that the ribbon conforms to the shape of the image on the imaging device in the impressed areas and the duplicate image formed on the copy sheet is of exceptional sharpness and cleanliness and free of background staining.

These and other objects and advantages are accomplished by the present invention in a manner which will be clear to those skilled in the art in the light of the following disclosure including the drawing, in which:

FIGURE 1 is a diagrammatic side view, to an enlarged scale, of a porous filament from which the woven fabric ribbons of the present invention are woven, and

FIG. 2 is a diagrammatic side view, to a diminished scale, of an inked woven fabric ribbon prepared according to the present invention.

The objects and advantages of the present invention are accomplished through the use of specially prepared filaments of film-forming material having a porous or cellular structure in which the porous network or cells are open and interconnected and adapted to receive and retain fluid ink compositions.

It has been discovered that fabrics formed from such porous filaments have many important properties heretofore unavailable with fabrics formed from conventional filaments. The present porous filaments may be formed s9 as to be several times lighter in weight or denier than conventional filaments of equal caliper, and thus fabrics formed therefrom are also several times lighter in weight or denier than conventional fabrics of equal caliper or thickness.

'ice

The filaments used for weaving, matting or otherwise forming the ink-impregnated fabrics of the present invention may be based upon any of the synthetic plastic materials which are conventionally extruded in the form of thin filaments. Prior to the extrusion process, the syn thetic plastic material is uniformly compounded with an amount of a pore-forming agent which may be a liquid or a gas but is preferably a finely powdered solid. When the compounded mixture is extruded in conventional manner the formed filaments have a porous or heterogeneous structure due to the fact that the pore-forming agent is liberated in the course of the extrusion process to leave pores or vacuities or open spaces and passages throughout the filaments.

Filaments formed in this manner are from two to ten or more times lighter than solid filaments of similar caliper or thickness but formed in conventional manner in the absence of pore-forming agents. Such light filaments may be woven or matted into fabrics of extreme lightness and high ink capacity. If desired, the porous filaments may first be longitudinally stretched to form two to five or more times their extruded length in order to reduce their caliper to any desired thickness and also to smooth the filament surface to some extent and reduce the size of any surface imperfections caused by the release of the poreforming agent without destroying the pore structure of the filaments. Fabrics woven from such porous stretched filaments are found to have high strength even though the filaments are of extremely fine caliper, and such fabrics are found to possess exceptionally good imaging properties with respect to sharpness and clarity.

The filaments used according to this invention may be formed of any of the conventional extrudable film-forming synthetic plastic materials including the polyolefins such as polyethylene and polypropylene; vinyl resins such as polystyrene, polyvinyl chloride, polyvinyl acetate and copolymers thereof, polyvinylidene chloride and the like; polyamides such as nylon; polyethylene terephthalate polyester (Dacron); polyacrylonitrile (Orlon); and cellulosic plastics such as rayon acetate and the like.

The pore-forming agents used according to the invention may be gaseous materials such as Freon, nitrogen, ammonia, carbon dioxide and the like; volatile liquids which are nonsolvents for the particular plastic used in combination therewith, such as water, toluene, ethanol, ammonium hydroxide and the like; or more preferably solid materials which decompose at the elevated temperatures of the extrusion process to liberate such gaseous or volatile liquid materials. The pore-forming agents are always liberated in the extrusion process in the form of gases. They are uniformly dispersed in the extrusion composition prior to extrusion and are maintained in a finely dispersed state due to the elevated pressures maintained in the extrusion machine. As soon as the composition is extruded into atmospheric pressure the gases are liberated to leave behind a porous network within the formed fibers. Where the pore-forming agent is a volatile liquid or heat-decomposable solid, the temperature at which the extrusion composition is maintained within the extrusion machine to melt the synthetic plastic, generally between about C. and 300 C., is sulficient to vaporize or decompose the agent to form the gases which are maintained dispersed throughout the composition due to the existing pressure which may range anywhere from slightly above atmospheric pressure to a pressure of 40 or 50 atmospheres.

The preferred pore-forming agents are solid powder compositions which are commercially available and which decompose at elevated temperatures to evolve a gas. Illustrative materials include p,p0xy-bis (benzenesulfonyl hydrazide) which is sold by Naugatuck Chemical Co. under the trademark Celogen, N,N dimethyl-N,N' dinitroso terephthalamide, diazoaminobenzene, dinitrosopentamethylenitetramine and various other known blowing agents which decompose at temperatures above about 90 C. to evolve a gas such as nitrogen, a nitrogen oxide, carbon dioxide, water vapor or the like.

The amount of pore-forming agent used depends to a large degree upon the nature of the plastic and pore-forming materials used and the strength and ink capacity desired. In general the pore-forming agent may be added in amounts ranging from about 0.01 to 15 parts by weight based upon the total weight of the extrusion composition. The prefer-red range is from about 1 to about '5 parts by weight.

The present filaments are formed by adding the desired amount of pore-forming agent, preferably in the form of finely divided solid particles, to the plastic material which is also preferably in solid particulate form. The mixture is agitated to obtain uniform dispersion and is then introduced into the extrusion machine where the high temperatures melt the plastic material and reduce the poreforming agent to a gas which is maintained dispersed within the plastic material by the elevated pressure in the extrusion machine. The mixture is then extruded in conventional manner through small orifices and the gaseous agent escapes from the extruded filaments leaving behind a porous ink-receptive network within each filament.

The filaments are then passed through a liquid coolant such as water or a salt solution and may thereafter be woven or matted into fabrics. If desired, the filaments may be stretched by passing them over rollers, contacting them with steam or other warm atmosphere, and then causing a tension to be drawn between the rollers to stretch the filaments to the desired degree whereby the caliper and denier of the filaments is reduced while the porosity thereof is also reduced but is still maintained. Such stretching processes are conventional in the art with solid filaments.

According to the preferred form of the present invention the porous filaments are either extruded or thereafter stretched so as to form filaments having a denier ranging between about 0.5 and 4. Such filaments are then matted to for-m fabrics or more preferably are twisted together in groups of from about to 40 to form multifilament strands which are then woven together or in admixture with strands of conventional solid filaments to form fabrics of exceptional lightness and ink capacity.

The fabric is then impregnated in conventional manner with a conventional liquid ribbon ink composition such as oil and coloring matter and will absorb from two to four or more times as much ink as conventional ribbons of equal caliper. The ink is held not only on the surface of the filaments and in the spaces between the filaments and strands, as is the case with conventional ribbons, but also within the porous network of each of the filaments. The ink so retained is squeezed from the filaments under pressure and the excess ink is then reabsorbed by the filaments and distributed by capillary action so that the imaging strength of the ribbon tends to remain uniform and the effective life of the ribbon is extended due to the migration of ink from the unused to the used parts of the ribbon.

While the present invention is concerned primarily with the production of woven typewriter ribbons which generally have a width of about 0.5 inch, it should be understood that the invention also applies to the production of non-woven matted or felted fabric ribbons and to ribbons for use in other duplicating machines such as chain printers and the like in which case the ribbons are of the required width which ranges in many cases up to 13 or more inches.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

l. A novel pressure-sensitive inked fabric material comprising a multiplicity of interconnected filaments consisting essentially of synthetic plastic material, said filaments being stretched to increase their strength and to reduce their caliper and surface irregularities and containing an internal porous network of open interconnected cells and having within the cells thereof a liquid, pressure-exudable ink composition said fabric material having an ink capacity at least twice as great as conventional fabrics of equal caliper and having improved imaging properties due to the strength and compressibility of the stretched porous filaments under the effect of imaging pressure.

2.. A novel pressure-sensitive inked fabric material according to claim 1 in which the synthetic plastic material is a polyolefin.

3. A novel pressure-sensitive inked fabric material according to claim 1 in which the ink composition comprises oil and coloring matter.

4. A novel pressure-sensitive inked fabric material according to claim 1 in which the filaments are matted together in the fabric.

5. A novel pressure-sensitive inked fabric material according to claim 1 in which the filaments are woven together in the fabric.

6. A novel pressure-sensitive inked fabric material according to claim 1 in which the filaments are present in multi-filament threads which are woven together in the fabric.

7. A novel pressure-sensitive inked fabric material according to claim 6 in which the filaments have a denier of from about 0.5 to 4 and the threads contain from about 10 to 40 filaments each.

8. The method of making pressure-sensitive inked fabric materials which comprises the steps of preparing an extrudable fiber-forming composition by uniformly mixing a composition consisting essentially of synthetic plastic and from 0.01 to 15 parts by weight of a blowing agent which is a gas at temperatures above about C., heating said composition to a temperature above about C. to melt the synthetic plastic while maintaining the composition under elevated pressure whereby the gas is maintained dispersed in the synthetic plastic, extruding said composition into atmospheric pressure whereby said gas escapes to form filaments of said synthetic plastic, said filaments containing an internal porous network of open interconnected cells, longitudinally stretching said filaments to increase their strength, reduce their caliper and reduce their surface irregularities, forming said filaments into a fabric, and impregnating said fabric with a liquid ink composition which is absorbed within the cells of the synthetic plastic filaments and which is exudable therefrom under the effects of imaging pressure, said fabric material having an ink capacity at least twice as great as conventional fabrics of equal caliper and having improved imaging properties due to the strength and compressibility of the stretched porous filaments under the effects of imaging pressure.

9. The method of making pressure-sensitive inked fabric materials which comprises the steps of preparing an extrudable fiber-forming composition by uniformly mixing a composition consisting essentially of synthetic plastic and from 0.01 to 15 parts by weight of a solid particulate blowing agent which evolves a gas when heated to temperatures above about 90 C., heating said composition to a temperature above about 125 C. to melt the synthetic plastic and evolve said gas while maintaining the composition under elevated pressure whereby the gas is maintained dispersed in the synthetic plastic, extruding said composition into atmospheric pressure whereby said gas escapes to form filaments of said synthetic plastic, said filaments containing an internal porous network of open interconnected cells, longitudinally stretching said filaments to increase their strength, reduce their caliper and reduce their surface irregularities, forming said filaments into a fabric, and impregnating said fabric with a liquid ink composition which is absorbed within the cells of the synthetic plastic filaments and which is exudable therefrom under the effects of imaging pressure, said fabric material having an ink capacity at least twice as great as conventional fabrics of equal caliper and having improved imaging properties due to the strength and compressibility of the stretched porous filaments under the effects of imaging pressure.

10. The method of making pressure-sensitive inked fabric materials which comprises the steps of preparing an extrudable fiber-forming composition by uniformly mixing a composition consisting essentially of synthetic plastic and from 0.01 to 15 parts by weight of a blowing agent which is a gas at temperatures above about 90 0., heating said composition to a temperature above about 125 C. to melt the synthetic plastic while maintaining the composition under elevated pressure whereby the gas is maintained dispersed in the synthetic plastic, extruding said composition into atmospheric pressure whereby said gas escapes to form filaments of said synthetic plastic, said filaments containing an internal porous network of open interconnected cells, longitudinally stretching said filaments to increase their strength, reduce their caliper and reduce their surface irregularities, twisting said filaments together to form multi-filament threads, weaving said filaments to form a fabric, and impregnating said woven fabric with a liquid ink composition which is absorbed within the cells of the synthetic plastic filaments and which is exudable therefrom under the effects of imaging pressure, said fabric material having an ink ca pacity at least twice as great as conventional fabrics of equal caliper and having improved imaging properties due to the strength and compressibility of the stretched porous filaments under the effects of imaging pressure.

11. The method of making pressure-sensitive inked fabric materials which comprises the steps of preparing an extrudable fiber-forming composition by uniformly mixing a composition consisting essentially of solid particulate synthetic plastic and from 0.01 to 15 parts by weight of a solid particulate blowing agent which evolves a gas when heated to temperatures above about C., heating said composition to a temperature above about C. to melt the synthetic plastic and evolve said gas While maintaining the composition under elevated pressure whereby the gas is maintained dispersed in the synthetic plastic, extruding said composition into atmospheric pressure whereby said gas escapes to form filaments of said synthetic plastic having a denier of from about 0.5 to about 4, said filaments containing an internal porous network of open interconnected cells, longitudinally stretching said filaments to increase their strength, reduce their caliper and reduce their surface irregularities, twisting said filaments together to form threads containing from about 10 to about 40 filaments, weaving said filaments to form a fabric, and impregnating said woven fabric with a liquid ink composition which is absorbed within the cells of the synthetic plastic filaments and which is exudable therefrom under the effects of imaging pressure, said fabric material having an ink capacity at least twice as great as conventional fabrics of equal caliper and having improved imaging properties due to the strength and compressibility of the stretched porous filaments under the effects of imaging pressure.

References Cited by the Examiner UNITED STATES PATENTS 1,427,330 8/1922 Rousset 264-54 2,167,990 8/1939 Neidich 197172 3,022,880 2/1962 Newman 11736.1 X 3,117,018 1/1964 Strauss 1l736.1

MURRAY KATZ, Primary Examiner. 

1. A NOVEL PRESSURE-SENSITIVE INKED FABRIC MATERIAL COMPRISING A MULTIPLICITY OF INTERCONNECTED FILAMENTS CONSISTING ESSENTIALLY OF SYNTHETIC PLASTIC MATERIAL, SAID FILAMENTS BEING STRETCHED TO INCREASE THEIR STRENGTH AND TO REDUCE THEIR CALIPER AND SURFACE IRREGULARITIES AND CONTAINING AN INTERNAL POROUS NETWORK OF OPEN INTERCONNECTED CELLS AND HAVING WITHIN THE CELLS THEREOF A LIQUID, PRESSURE-EXUDABLE INK COMPOSITION SAID FABRIC MATERIAL HAVING AN INK CAPACITY AT LEAST TWICE AS GREAT AS CONVENTIONAL FABRICS OF EQUAL CALIPER AND HAVING IMPROVED IMAGING PROPERTIES DUE TO THE STRENGTH AND COMPRESSIBILITY OF THE STRETCHED POROUS FILAMENTS UNDER THE EFFECT OF IMAGING PRESSURE. 